Waveguide technology, otherwise known as edge-lit, light pipe, light guide or fiber optic light transmission is a mature technology with many applications in use such as providing light along long distances by way of a fiber optic cable, illuminating a back-lit advertisement by means of an edge-lit panel behind the advertisement, or providing illumination as a lighting fixture. In use as a lighting fixture, or luminaire, light is directed into the end of a nominally transparent object that comprises the waveguide, generally in the form of a panel or rod, and is typically comprised of plastic or glass. Due to the phenomenon described as total internal reflection, or TIR, light is able to bounce within the confines of the waveguide since the angle of incidence of the light approaching an interior surface of the waveguide prevents the light from escaping, as it bounces off the interior surface of the waveguide back into the body of the waveguide, where it continues to do so as it travels the length of the waveguide; by this means does light travel the extent of the waveguide, such that it guides light waves within itself.
The major surface or surfaces of the waveguide are nominally glossy and transparent in order to maintain this effect, however in order to extract the light from the waveguides, portions of the surface where light is desirably extracted from require perturbations that disrupt the travel of light from TIR and instead allow the light to pass through the interior surface of the waveguide and exit as light. These perturbations may come in many forms such as surface frosting, spot facing, etching, crazing, or any other irregularity on the surface of the waveguide that may be produced by a molding process, acid etching, silk-screening, chemical reaction or mechanical process and the like.
Light-emitting diode, or LED, light sources lend themselves to transmitting light through a waveguide as their relatively small width works well in conjunction with the normally small thickness of the waveguide, the LED width typically being a little smaller than the waveguide and, in typical terms, the LED being approximately 2 mm wide and the waveguide being anywhere from 3 to 6 mm wide, though these figures may vary by design. LEDs are typically mounted to a printed circuit board, or PCB.